Monocyte chemotactic and activating factor/monocyte chemoattractant protein (MCAF/MCP-1) is a member of the beta (C-C) subfamily of chemokines. The biological roles played by MCAF/MCP-1 in a number of inflammatory and noninflammatory diseases states is not well known. Several studies have confirmed that inflammation is present in the airways of subjects with atopic asthma and with chronic bronchitis. Analysis of bronchoalveolar lavage fluid (BALF) is an effective method of sampling lower respiratory tract inflammation. The aim of this study was to examine associations among MCAF/MCP-1, BALF cells and spirometry parameters and bronchial hyperresponsiveness in patients with atopic asthma and chronic bronchitis. Twenty patients with atopic asthma, 10 patients with chronic bronchitis and 10 patients of the control group, took part in this study. An ELISA test was used to assess MCAF/MCP-1 in BALF. The levels of MCAF/ MCP-1 (mean +/- SEM) were 150 +/- 18.6 pg/ml in patients with atopic asthma, 320 +/- 39.7 pg/ml in chronic bronchitis and 74.9 +/- 3.3 pg/ml in the control group (p < 0.05). When all patients with disease were considered, there was negative correlation with FEF50 (Kendall's correlation coefficient = - 0.4; p < 0.01). Regression analysis has shown that a level of MCAF/MCP-1 over 100 pg/ml was correlated with duration of illness (Pearson's correlation coefficient = 0.7; p < 0.02). In conclusion, MCAF/MCP-1 probably possesses proinflammatory properties in atopic asthma and chronic bronchitis. The elevated level of this chemokine may support the clinical suspicion of specific diagnosis.